Liquid air engine could solve pollution problems in the future

A revolutionary engine is set to help wind machines store surplus energy and could also play a major part in solving the problems of car pollution in the future.

The liquid air engine, invented by Cambridge firm Epicam, is to be trialled by the world’s leading diesel engine manufacturer, Cummins.

The system is driven by wind and has an integrated energy storage and power regeneration system.

The energy is stored in the form of liquid air which is produced from a compact air liquefaction unit driven directly by the wind turbine. This enables the machine to store surplus energy under good wind conditions and regenerate power for delivery in the absence of wind, thus providing continuous power regardless of wind conditions.

Epicam was among 12 winning technology companies from more than 100 internationally sourced entries for the Cummins Environmental Gateway Competition.

Tony Dye, senior member of Wolfson College, Cambridge, and managing director of Epicam, said: “We saw the contract alert from Cambridge Cleantech, entered the competition and have come out as winners, which we’re delighted about. I will be working closely with Cummins to start trials soon.”

The engine operates at speeds up to 20,000 revolutions per minute, driving a high-speed generator and demonstrating a power density several times greater than the best internal combustion engines.

Epicam believes that this technology will form the basis of the next generation of industrial, domestic and transport power.

The delivery is based upon the phase change in air in much the same way as the railway era came about as a result of the discovery of utilising the energy from the same phase change from liquid to gas in water.

At the core of the technology developed by Epicam is a pair of rotors, one lobed and the other with pockets which counter-rotate together so that lobes and pockets interact in a unique manner without actual contact rotor to rotor or with their housing.

This provides compression or expansion in compressible fluids like air without internal friction from mechanical contact.

These rotor pairs are used in a sequence of compression and expansion stages to compress air, remove the heat of compression and then expand it to produce cooling. That ultimately results in driving the temperature of the air below its condensation point and enables it to be stored as liquid air.

The same type of rotors are used as an expansion engine to convert the pressure released from the liquid air when it is warmed to atmospheric temperature by local air.

Denis Ford, international sourcing leader at Cummins said: “We would like to thank Cambridge Cleantech for their brilliant support. Most especially, we would also like to congratulate Epicam on their success.”